Step 1: Understanding the Concept:
The question asks for the core argument of Emile Durkheim's famous sociological study, "Suicide" (1897).
Step 2: Detailed Explanation:
Durkheim's central thesis was to demonstrate that sociology was a legitimate science. To do this, he took a phenomenon that seemed intensely personal and individual—suicide—and showed that its rates could be explained by societal factors.
(A) It is based on individual mindset: This is a psychological explanation. Durkheim explicitly argued against this, stating that while individual psychology is involved in a specific case, it cannot explain the stable suicide rates across different societies and groups.
(B) It is based on biological anomaly: This is a biological explanation, which Durkheim also refuted using statistical data.
(C) It is influenced by social causes: This is the cornerstone of his theory. Durkheim identified two key social forces: social integration (the degree to which individuals are part of a group) and social regulation (the degree of external constraint on people). He argued that abnormally high or low levels of these social forces lead to different types of suicide (egoistic, altruistic, anomic, fatalistic). Thus, suicide is a social fact, explained by other social facts.
(D) It is more prevalent in western countries: This may have been an empirical observation Durkheim used as evidence, but it is not the \textit{cause}. The cause, according to him, was the specific social conditions (like higher individualism or 'anomie' in modern Western societies), not the geographical location itself.
Step 3: Final Answer:
According to Emile Durkheim, the cause of suicide lies not in the individual, but in social causes, specifically the levels of social integration and regulation.